Clinician’s Guide to Early Rule-out with High Sensitivity Troponin

June 23, 2017

Paralysis of analysis
This Clinician’s Guide summarizes the onslaught of high-sensitivity troponin (hs-Tn) studies and offers these best practices when considering MI rule-out strategies using hs-Tn.

1. There are differences in assays.  The hs-TnI performs better in early presenters; hs-TnT assay performs better in late presenters.  The assay currently approved in the US is hs-TnT.
2. Strategies combining clinical scoring systems, such as HEART, etc. plus biomarkers have greater diagnostic accuracy.
3. You must know the time of onset of symptoms.
4. The author favors strategies with serial hs-Tn testing.  This is especially important with early presenters (<2 hours) and with use of the hs-TnT assay (available in the US).
5. But there are reasonable single-troponin strategies.
   – If onset > 6 hours, then hs-TnI < 99th percentile upper reference limit (URL) is sufficient per European Society of Cardiology (ESC) guidelines.
   – If onset > 2 hours, a single hs-Tn I < 5ng/L is acceptable, but dropping the threshold to the assay’s lower limit of detection improves the NPV to 100%.
6. The allowable delta troponin depends on time from initial troponin. For hs-TnI, it is a delta of <2 ng/mL at 1-hour or < 3 ng/mL at 3-hours.  Or the ESC recommends the 3-hour delta hs-Tn be <99th percentile URL or < 50% of the URL. 

Spoon Feed
Consider these best practices when implementing a high sensitivity troponin strategy to rule out MI.  Read SGEM’s Oh Baby You’re Too Sensitive about hs-Tn.

Source
Clinician’s Guide to Early Rule-Out Strategies With High-Sensitivity Cardiac Troponin.  Circulation. 2017 Apr 25;135(17):1612-1616. doi: 10.1161/CIRCULATIONAHA.117.026717.

Co-written by Thomas Davis and Clay Smith.